On Mon, Sep 01, 2014 at 03:45:29PM +0100, Siluvery, Arun wrote:
> >>+ /*
> >>+ * Most of workarounds are masked registers;
> >>+ * to set a bit in lower 16-bits we set a mask bit in
> >>+ * upper 16-bits so we can take either of them as mask but
> >>+ * it doesn't work if the w/a is about clearing a bit so
> >>+ * use upper 16-bits to cover both cases.
> >>+ */
> >>+ mask = ro_data.init_context[i+1] >> 16;
> >
> >"Most" doesn't seem good here. Either it's "all" and we're happy, or we
> >need a generic way to describe the W/A (masked register or not). value +
> >mask is generic enough to code for both cases.
> >
> It seems some of them could be unmasked registers.
> We can use 'mask' itself to determine whether it is a
> masked/unmasked register. mask == 0 if it is an unmasked register.
I don't think we can use mask == 0 when it's an unmasked register. In
this case, we still need to be able to have a mask that tells us which
are the interesting bits in the value. If we want something generic that
can be applied to masked and unmasked register, we'll something like:
struct reg_wa {
unsigned int masked_register : 1;
u32 addr;
u32 mask;
u32 value;
};
So:
1. masked register case:
- masked_register = 1
- addr
- mask (selects the lower 16 bits that are coding for the W/A value)
- value (it only makes sense to some of the lower 16 bits set here)
2. 'normal' register case
- masked_register = 0
- addr
- mask
- value
>From that generic description you can cover all cases, eg.
1. the write for masked registers becomes: mask << 16 | value
2. the write for normal registers becomes: (read(addr) & ~mask) | value
2. check a W/A has been applied (both normal and masked register):
read(addr) & mask == value
We seem to have only masked registers atm, so it's fine to handle just
that case, but if you envision that we'll need more than masked
registers, we need a better W/A definition.
--
Damien
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